Printed thermoelectric devices to power wearables using body heat

Using the heat of the body to power small electronic devices has been a goal of developers for some time, especially as heart rate or respiration monitors consume only small amounts of power. But thermoelectric devices, which use differences in temperature to generate a flow of current, have always been too large and inflexible, and required materials too toxic to be useful for this. A team at Georgia Tech has now devised a way to make generator circuits that can be printed onto flexible materials and cut to size according to how much power is needed.

The circuits generate power through dots made up of layers of semiconducting polymers. Two types of polymer are used; n-type (which has excess electrons that can move along and between polymer chains), and p-type (which is deficient in electrons, leading to mobile positively-charged ‘holes’ that can move similarly). Printing these dots with an inkjet printer allows them to be closely spaced, maximising the heat collected per unit area and the resulting power output of the device.